Plate For A Heat Exchanger And Heat Exchanger Equipped With Such Plates

Abstract

The invention relates to a plate (4, 12, 14) intended to allow an exchange of heat between a first fluid and a second fluid flowing in contact with the plate (4, 12, 14), said plate (4, 12, 14) being configured to define a circuit (8) comprising a plurality of successive passageways (71, 72, 73, 74), inside which the first fluid flows in one direction of flow, changing its direction of flow from one passageway to the other, each of said passageways (71, 72, 73, 74) having a flow section for the first fluid. According to the invention, the flow section of one passageway (71, 72, 73, 74), known as the upstream passageway, is larger than the flow section of another passageway (71, 72, 73, 74), known as the downstream passageway, which is situated downstream of the upstream passageway in the direction of flow of the first fluid in the circuit (8). The invention also relates to a heat exchanger equipped with such plates.

Description

The invention relates to plates for heat exchangers and to plate heat exchangers, in particular for motor vehicles.

Exchangers, known as charge air coolers, permitting an exchange of heat between charge air, intended to supply the engine of the vehicle, and a coolant liquid are familiar in this field. They comprise a heat exchange array consisting of a stack of plates determining between them alternate circulation channels for the charge air and for the coolant liquid.

Charge air coolers with stacked plates, such as those referred to above, are familiar, in which each plate guides the coolant liquid in a circuit forming a plurality of passageways of identical cross section and in the interior of which passageways the coolant liquid circulates in a direction orthogonal to the flow of charge air. The coolant liquid changes its direction of circulation in each passageway.

The temperature of the coolant liquid increases as it flows through the circuit, which brings about a variation in its physical properties (in particular its density and its viscosity). When the physical properties of the charge liquid change, the loss of charge also fluctuates.

In the existing solutions, the widths of the passageways are identical within one and the same circuit and does not adapt to the fluctuation the losses of charge mentioned previously, the consequence of which is to impair the performance of the exchanger.

The losses of charge may, in fact, contribute in a positive manner to the thermal efficiency of the exchanger, in light of the knowledge that the greater the loss of charge, the more turbulent the mode of flow of the stream may be, which is favorable for the thermal exchange, at least within a certain limit.

However, the pumps that are used for the circulation of the coolant liquid possess limited characteristics, the intention being to avoid excessively compromising the consumption of energy obtain from the engine of the vehicle.

It has thus been established within the ambit of the invention that a favorable relationship existed between the change in the dimension of the flow sections of passageways and the fluctuation in the changes in the physical properties of the coolant fluid in order to reduce the total loss of charge in the circuit without excessively compromising the thermal performance of the exchanger.

The invention also relates to a plate intended to allow an exchange of heat between a first fluid and a second fluid circulating in contact with the plate, said plate being configured to define a circuit comprising a plurality of successive passageways, in which circuit the first fluid circulates in a direction of flow, changing its direction of flow from one passageway to the other, each of the passageways possessing a flow section for the first fluid.

According to the invention, the flow section of one passageway, known as the upstream passageway, is larger than the flow section of another passageway, known as the downstream passageway, which is situated downstream of the upstream passageway in the direction of flow of the first fluid in the circuit.

Thus, as it flows through the circuit, the first fluid circulates through passageways of which the flow section continues to reduce, the effect of which is to sustain the fluctuation in the losses of charge that are attributable to the increase in its temperature. The coefficient of loss of charge may then be kept relatively constant along the length of the circuit.

In the case of charge air coolers, the first fluid corresponds to a coolant liquid, and the second fluid corresponds to the charge air.

According to one aspect of the invention, said plate comprises an initial passageway and a final passageway, and the flow sections of the passageways decrease from one passageway to the other from the initial passageway towards the final passageway. They decrease, for example, in a linear or proportional manner.

According to another aspect of the invention, the flow section of the initial passageway is between 40 and 60% larger than the flow section of the final passageway.

According to one particular embodiment, said plate comprises four passageways, known as the first passageway, second passageway, third passageway and fourth passageway, the first passageway being connected to an inlet into the circuit, the second passageway being connected to the first passageway, the third passageway being connected to the second passageway and the fourth passageway being connected on the one hand to the third passageway and on the other hand to an outlet from the circuit. The flow section then continues to reduce from the first passageway as far as the fourth passageway.

Advantageously, the flow section of the first passageway is between 5 and 15% larger than the flow section of the second passageway. Still advantageously, the flow section of the second passageway is between 20 and 40% larger than the flow section of the third passageway. In particular, the flow section of the third passageway is between 5 and 15% larger than the flow section of the fourth passageway.

According to one illustrative embodiment, the distance between the margins defining the first passageway is between 30 and 35 mm, the distance between the margins defining the second passageway is between 27 and 32 mm, the distance between the margins defining the third passageway is between 22 and 25 mm and/or the distance between the margins defining the fourth passageway is between 20 and 23 mm. The margins defining a passageway are, in particular, parallel to one another such that the flow section of one passageway is constant. The flow section is measured in a plane perpendicular to an extension plane of the plate.

According to a further aspect of the invention, the passageways comprise baffles for disrupting the flow of fluid.

The invention also relates to a heat exchanger, intended in particular for a motor vehicle, comprising plates as defined previously, at least two of said plates being stacked one on top of the other in a pair of plates, such that the circuit of one of the two plates is a mirror-image of the circuit of the other of the two plates. It will be appreciated here that two plates forming a pair of plates are stacked one on top of the other such that their circuit together form a circulation channel for the first fluid.

Other characterizing features and advantages of the invention will become even more evident from a perusal of the following description of illustrative embodiments provided by way of example with reference to the accompanying figures. In these figures:

FIG. 1 is a view in perspective illustrating as an exploded view a heat exchanger according to the invention comprising plates having four passageways;

FIG. 2 is a view from above of a plate comprising four passageways, intended to illustrate the differences in the flow sections of the different passageways according to the invention.

As illustrated in FIG. 1, the invention relates to a heat exchanger 1 permitting an exchange of heat between a fluid to be cooled, in particular a gas G, and a coolant liquid C. It can be a charge air cooler, inside which a flow of compressed air intended to supply an internal combustion engine, for example an engine of a motor vehicle, is cooled by a cooling liquid, in particular a mixture of water and glycol.

The exchanger 1 comprises an array 2 for the exchange of heat constituted by a stack of plates 4 determining between them alternate circuits 6, 8 for the fluid to be cooled G and for the coolant liquid. The array in this case is of generally parallepipedal shape and exhibits an outlet surface 10 and an opposing inlet surface, although not depicted here, for the fluid to be cooled. It is terminated on both sides of the stack by a plate, known as the upper plate, 12, and by a plate, known as the lower plate, 14.

The exchanger 1 can also comprise a housing 5, inside which the array 2 is situated. It guides the fluid to be cooled between the plates from the inlet surface to the outlet surface 10 of the array 2. It is constituted in this case by two lateral walls 18, each coming up against the lateral edges 16, 16′ of the plates 4, 12, 14, by an upper wall 20, coming into contact with the upper plate 12, and by a lower wall 22, coming into contact with the lower plate 14. The upper wall 20 can be provided with openings 24, 26 permitting the passage, both outgoing and incoming, of the coolant liquid C into the array 2.

The exchanger 1 may also comprise outlet and/or inlet pipe connections 28, 30 for the coolant liquid communicating with said openings 24, 26 provided in the housing.

The different component parts of the exchanger are made of aluminum or an alloy of aluminum, for example. In particular, they are brazed to one another.

Each plate 4, 12, 14 includes a bottom 31, for example, which is substantially plane, surrounded by a peripheral margin 32 terminated by a flat surface 34, permitting the brazing of the plates to one another. The circuit 8 for the coolant liquid is defined, on the one hand, by said peripheral margin 32 and, on the other hand, by one or a plurality of central margins 60, 60′, for example arising from the material of the bottom 31 of the plate.

The plates 4, 12, 14 are grouped together in pairs and are assembled via their flats 34 and/or the margins 60, 60′. In this way, the circuit of one upper plate 4 and of one lower plate 4 of one and the same pair of plates complement one another in order to constitute a circulation channel for the coolant liquid C. In other words, the plates 4 are thus stacked by pairs, in such a way that the circuit 8 for the coolant liquid C of one of the two plates is situated opposite the circuit 8 for the coolant liquid C of the other of the two plates of one and the same pair, in order to form a circulation channel for coolant liquid C. The circuits 6 for the circulation of the fluid to be cooled are provided between two plates 4 opposite two adjacent pairs of plates 4.

In the illustrated example, the upper plates 12 and the lower plates 14 of the stack are assembled with the upper 20 and lower 22 walls of the housing in order to define a circulation channel for coolant liquid.

The plates 4, 12, 14 possess the general shape of an elongated rectangle, for example, having two large sides and two small sides, each plate including two bosses 38, a first of the bosses 38 exhibiting an inlet 42 into the circulation channel 8 for coolant liquid C, and the other of the bosses 38 exhibiting an outlet 40 from the circulation channel for coolant liquid C.

The bosses 38 are situated along one and the same small side of the plate 4, 12, 14. They are penetrated here by an opening 50 for the passage of the coolant liquid C, and they are are intended to come into contact with the bosses 38 of one adjacent plate 4 so as to form respectively an inlet collector 44 and an outlet collector, not illustrated here, for the coolant fluid C. The inlet collector 44 discharges, for example, into the inlet pipe connection 30 via the inlet opening 26 of the housing, and/or the outlet collector discharges, for example, into the outlet pipe connection 28 via the outlet opening 24 of the housing.

In other words, the coolant fluid makes its way into the array via the inlet pipe connection 30 and is then distributed between the plates 4 in the circuits 8 for the circulation of coolant liquid via the inlet collector 44. It then flows in the circuits 8 for the circulation of the coolant liquid C from their inlets 42 as far as their outlets 40, where it penetrates into the outlet collector. It then exits from the exchanger through the outlet pipe connection 30.

The bosses 38 of two pairs of plates 4 determine between them the height of the circulation circuits 6 for the fluid to be cooled.

An inlet collection box and an outlet collection box (not illustrated here) can be adapted to the periphery of the housing in order to deliver and remove the fluid to be cooled.

The exchanger can also comprise secondary exchange surfaces, for example corrugated baffles inserted between the plates 4 inside the circuits 6 for the circulation of the fluid to be cooled G. These baffles permit the flow of the liquid to be cooled G to be disrupted in such a way as to improve the thermal exchange between the two fluids.

Each plate 4, 12, 14 comprises, for example, corrugations 52 arranged inside the circuits 8 for the circulation of the coolant fluid C. These corrugations 52 extend between the pockets 38 constituting the inlet collector and the outlet collector 44 for the coolant liquid C and the second longitudinal extremity of the plates 4, 12, 14. The corrugations 52 arise, for example, from the material of the bottom 31 of the plates 4, 12, 14, in particular by deep-drawing the plates 4, 12, 14.

The circuit 8 defined by the plates 4, 12, 14 makes it possible to guide the coolant liquid C into a number n of successive passageways, in this case being four in number, in which the coolant liquid enters the inlet 42 into and the outlet 40 from the circuit 8. Two adjacent passageways are separated, for example, by the margins 32, 60, 60′ of the plates 4, 12, 14.

The passageways are arranged parallel to one another in an extension direction, in this case being the large side of the plates. They can also be provided in series one after the other.

The margins 60, 60′ are thus oriented along the large side of the plates 4 in order to define a serpentine circulation of the coolant liquid inside each of the passageways of each of the circuits 8 for the circulation of the coolant liquid C. Certain 60 of the margins extend from the edge 16 provided with the bosses 38 towards the opposite edge 16′, while leaving a passageway free to enable the fluid to flow from the passageway present on one side of the margin 60 to the other passageway. They alternate with margins 60′ extending from the edge 16′ opposite that 16 provided with the bosses 38 towards the edge 16 provided with the bosses 38, while leaving a passageway free to enable the fluid to flow from the passageway present on one side of the margin 60′ to the other passageway.

In the example illustrated in FIGS. 1 and 2, where the plate is provided with four passageways, it is possible to observe a first passageway 71, or initial passageway 71, extending from the inlet 40 as far as the edge 16′ opposite that 16 provided with the bosses 38; a second passageway 72 connected to the first and extending from the edge 16′ opposite the edge 16 provided with the bosses 38 as far as the edge 16 provided with the bosses 38; a third passageway 73 connected to the second passageway and extending from the edge 16 provided with the bosses 38 as far as the edge 16′ opposite that 16 provided with the bosses 38; and a fourth passageway 74 connected, on the one hand, to the third passageway 73 and, on the other hand, to the outlet 42, such that it extends from the edge 16′ opposite the edge 16 provided with the bosses 38 as far as the edge 16 provided with the bosses 38.

The circulation of the fluid to be cooled D inside the circuits 6 for the circulation of the fluid to be cooled thus takes place in a direction that is generally perpendicular to that of the flow of the coolant liquid, the coolant liquid changing its direction of flow from one passageway to the other.

A plate according to the invention is depicted in FIG. 2. Such a plate exhibits a length L in the direction of extension of the passageways and a length l in a direction D orthogonal to the direction of extension of the passageways. Inside the exchanger, the direction D thus corresponds to the direction of flow of the fluid to be cooled. In the same way, in a plate comprising n passageways, each passageway exhibits a width In corresponding to the distance in the direction D between two margins 32, 60, 60′ defining this passageway. Thus, in the illustrated example, the first passageway 71 exhibits a width 11, the second passageway 72 a width 12, the third passageway a width 13, and the fourth passageway 74 a width 14.

According to the invention, the flow section of a passageway, known as the upstream passageway, is larger than the flow section of another passageway, known as the downstream passageway, which is situated downstream of the upstream passageway in the direction of flow of the coolant fluid in the circuit 8 for the circulation of the coolant liquid. Given that the coolant liquid flows from the initial passageway towards the final passageway, that is to say in this case from the first passageway 71 towards the fourth passageway 74, the flow section decreases from the first passageway 71 towards the fourth passageway 74. An optimization of the loss of charge/thermal performance ratio can thus also be noted.

The flow section of a passageway is defined by its width multiplied by the height of the margins 32, 60, 60′ which define it. Since the margins 32, 60, 60′ in this case are substantially parallel to each other and of identical height, the comparison of the passageway widths is equivalent in the rest of the description to a comparison of the flow sections of each passageway.

According to one aspect of the invention, the width l₁ of the first passageway 71 is between 5 and 15% larger than the width l₂ of the second passageway 72.

The width l₂ of the second passageway in this case is between 20 and 40% larger than the width l₃ of the third passageway 73.

The width l₃ of the third passageway 73 is, for example, between 5 and 15% larger than the width l₄ of the fourth passageway 74.

In one illustrative embodiment, the width of the initial passageway, in this case the first passageway 71, is between 40 and 60% larger than the width of the final passageway, in this case the fourth passageway 74.

In the example illustrated in FIG. 2, the plate the width l of the plate 4, 12, 14 is, in particular, equal to 120 mm, and its length L is, for example, equal to 200 mm. In this case, the width l₁ of the first passageway 71 lies, in particular, between 30 and 35 mm, the width l₂ of the second passageway 72 lies, for example, between 27 and 32 mm, the width l₃ of the third passageway 73 lies, in particular, between 22 and 25 mm and the width l₄ of the fourth passageway 74 lies advantageously between 20 and 23 mm.

Claims

1. A plate (4, 12, 14) intended to allow an exchange of heat between a first fluid and a second fluid (C, G) flowing in contact with the plate (4, 12, 14), the plate (4, 12, 14) being configured to define a circuit (8) comprising a plurality of successive passageways (71, 72, 73, 74), inside which the first fluid (C) flows in one direction of flow, changing its direction of flow from one passageway to the other, each of the passageways (71, 72, 73, 74) having a flow section for the first fluid (C), wherein the flow section of one passageway (71, 72, 73, 74), is an upstream passageway and is larger than the flow section of another passageway (71, 72, 73, 74), which is a downstream passageway, and is situated downstream of the upstream passageway in the direction of flow of the first fluid in the circuit (8).

2. The plate (4, 12, 14) as claimed in claim 1, comprising an initial passageway (71) and a final passageway (74), the flow sections of the passageways (71, 72, 73, 74) decreasing from one passageway to the other from the initial passageway (71) towards the final passageway (74).

3. The plate (4, 12, 14) as claimed in claim 2, in which the flow section of the initial passageway (71) is between 40% and 60% larger than the flow section of the final passageway (74).

4. The plate (4, 12, 14) as claimed in claim 1, comprising four passageways (71, 72, 73, 74), further defined as a first passageway (71), a second passageway (72), a third passageway (73) and a fourth passageway (74), with the first passageway (71) being connected to an inlet (42) into the circuit (8), the second passageway (72) being connected to the first passageway (71), the third passageway (73) being connected to the second passageway (72) and the fourth passageway (74) being connected, on the one hand, to the third passageway (73) and, on the other hand, to an outlet from the circuit (40).

5. The plate (4, 12, 14) as claimed in claim 4, in which the flow section of the first passageway (71) is between 5% and 15% larger than the flow section of the second passageway (72).

6. The plate (4, 12, 14) as claimed in claim 4, in which the flow section of the second passageway (72) is between 20% and 40% larger than the flow section of the third passageway (73).

7. The plate (4, 12, 14) as claimed in claim 4, in which the flow section of the third passageway (73) is between 5% and 15% larger than the flow section of the fourth passageway (74).

8. The plate (4, 12, 14) as claimed in claim 4, in which a distance between margins (38, 60) defining the first passageway (71) is between 30 mm and 35 mm, a distance between margins (60, 60′) defining the second passageway (72) is between 27 mm and 32 mm, a distance between margins (60, 60′) defining the third passageway (73) is between 22 mm and 25 mm and/or a distance between margins (60, 38) defining the fourth passageway (74) is between 20 mm and 23 mm.

9. The plate (4, 12, 14) as claimed in claim 1, inside which the passageways (71, 72, 73, 74) comprise baffles (52) for the flow of the fluid.

10. A heat exchanger (1), for a motor vehicle, the heat exchanger (1) comprising plates (4) as claimed in claim 1, with at least two of the plates (4) being stacked one on top of the other in a pair of plates, such that the circuit (8) of one of the two plates (4) is a minor-image of the circuit (8) of the other of the two plates (4).

11. The plate (4, 12, 14) as claimed in claim 2, comprising four passageways (71, 72, 73, 74), further defined as a first passageway (71), a second passageway (72), a third passageway (73) and a fourth passageway (74), with the first passageway (71) being connected to an inlet (42) into the circuit (8), the second passageway (72) being connected to the first passageway (71), the third passageway (73) being connected to the second passageway (72) and the fourth passageway (74) being connected, on the one hand, to the third passageway (73) and, on the other hand, to an outlet from the circuit (40).

12. The plate (4, 12, 14) as claimed in claim 5, in which the flow section of the second passageway (72) is between 20% and 40% larger than the flow section of the third passageway (73).

13. The plate (4, 12, 14) as claimed in claim 12, in which the flow section of the third passageway (73) is between 5% and 15% larger than the flow section of the fourth passageway (74).

14. The plate (4, 12, 14) as claimed in claim 5, in which a distance between margins (38, 60) defining the first passageway (71) is between 30 mm and 35 mm, a distance between margins (60, 60′) defining the second passageway (72) is between 27 mm and 32 mm, a distance between margins (60, 60′) defining the third passageway (73) is between 22 mm and 25 mm and/or a distance between margins (60, 38) defining the fourth passageway (74) is between 20 mm and 23 mm.

15. The plate (4, 12, 14) as claimed in claim 2, inside which the passageways (71, 72, 73, 74) comprise baffles (52) for the flow of the fluid.